Long-term stability studies using radiopharmaceuticals: consequence of using multiply tritiated compounds, with an application to fluocinolone acetonide.

The use of multiply tritiated radiopharmaceutical compounds for long-term stability studies should be avoided because different radiolabeled products are produced by radioactive decay than by chemical degradation. This is demonstrated by showing that doubly tritiated fluocinolone acetonide and (14)C-labeled fluocinolone acetonide have different shelf lives and that the tritiated compound affords additional degradation products not seen in reaction of the (14)C-labeled drug after 26 months.